The present invention relates to an X-ray fluorescence spectrometer for analyzing the composition of and the area density of a sample based on the FP method and a program for use therein.
The X-ray fluorescence spectrometer has hitherto been well known, which analyzes the composition of and the area density of a sample by the utilization of the fundamental parameter method (hereinafter referred to as “FP method”). According to the FP method, based on the assumed composition, the assumed concentrations of elements in other words, the theoretical intensity of the secondary X-rays emanated from elements contained in the sample is calculated and the assumed composition is successively approximately modified and calculated so that the calculated theoretical intensity and the converted and measured intensity, which has been detected by a detecting device and then converted in a theoretical intensity scale, can match with each other, thereby calculating the concentration of each of the elements contained in the sample, the composition of the sample in other words. In calculating the theoretical intensity referred to above, the computation model is employed, in which the sample that is infinitely large in size is uniformly irradiated with parallel primary X-rays and secondary X-rays emanated from a portion thereof are observed.
In practice, however, not only the size of the sample, but the radiation area of primary X-rays is finite and the incident angle of primary X-rays changes with the position of incidence thereof. Accordingly, the intensity of the secondary X-rays emanating actually from the sample does not completely match with the intensity of the secondary X-rays emanated in the previously discussed computation model. While this is referred to as the geometry effect, the analysis will not result in presentation of a sufficiently accurate composition of the sample unless the theoretical intensity is computed with the geometry effect taken sufficiently into consideration in conformity with the reality.
In view of the foregoing, in order to enable computation of the theoretical intensity with the geometry effect taken into consideration, a software application, which is tradenamed “UniQuant”, is presented from Omega Data System. According to this software application, the theoretical intensity is computed with the use of the sensitivity curve, which has been determined in the direction of depth of the sample by systematically changing the thickness thereof.
However, the sensitivity curve in the direction of depth varies depending on the secondary X-rays and the composition of an object to be analyzed, proper application of this conventional technique to various kinds of samples requires a number of sensitivity curves to be determined ahead of time and this is not realistic.